Function Design of Mechatronic Systems for Human-Robot Collaboration

Traditionally, robots have been caged off from human activity but, recently, improvements in advance robotic technology as well as the introduction of new safety standards, have allowed the possibility of collaboration between human workers and robotic systems. The introduction of Human-Robot Collaboration has the potential to increase the quality and the flexibility of the production process while improving the working condition of the operators. However, traditional industrial robots are typically characterized by small payload and small reachable workspace that reduce the range of possible applications. These drawbacks can overcome the advantages related to a collaborative task and make the collaboration not effective. This work aims at analyzing innovative mechatronic solutions capable of increasing the workspace and the versatility of the system with the final goal of creating effective collaborations with humans. Cable driven Parallel Robots (CDPRs) are considered a promising technology able to satisfy these requirements. In fact, compared to rigid serial and parallel robots, they have several advantages such as large workspaces, high payloads per unit of weight, ease of construction, versatility and affordable costs. This work presents two innovative solutions of CDPR able to enlarge the workspace, improve the versatility and reduce the collisions risk. The first solution consists of a cable-suspended parallel robot with a reconfigurable end-effector whereas the second solution is an innovative model of cable-driven micro-macro robot. In the first part of the thesis, the kinematic and dynamic models of these innovative systems are presented and analyzed in order to characterize their capability. Trajectory planning and optimal design are addressed with the purpose of maximizing the performance of the systems. The last part of the thesis deals with the design of a novel family of Intelligent CAble-driven parallel roBOTs whose architecture and control are conceived to maximize the robot versatility to the task to be performed and the environment in which the robot is intended to operate

Design and optimization of heat exchangers for Organic Rankine cycles

Design of power plant and heat exchangers. Optimization with multi-objective genetic algorithm. Selection of optimal working fluid

Function Design of Mechatronic Systems for Human-Robot Collaboration

Traditionally, robots have been caged off from human activity but, recently, improvements in advance robotic technology as well as the introduction of new safety standards, have allowed the possibility of collaboration between human workers and robotic systems. The introduction of Human-Robot Collaboration has the potential to increase the quality and the flexibility of the production process while improving the working condition of the operators. However, traditional industrial robots are typically characterized by small payload and small reachable workspace that reduce the range of possible applications. These drawbacks can overcome the advantages related to a collaborative task and make the collaboration not effective. This work aims at analyzing innovative mechatronic solutions capable of increasing the workspace and the versatility of the system with the final goal of creating effective collaborations with humans. Cable driven Parallel Robots (CDPRs) are considered a promising technology able to satisfy these requirements. In fact, compared to rigid serial and parallel robots, they have several advantages such as large workspaces, high payloads per unit of weight, ease of construction, versatility and affordable costs. This work presents two innovative solutions of CDPR able to enlarge the workspace, improve the versatility and reduce the collisions risk. The first solution consists of a cable-suspended parallel robot with a reconfigurable end-effector whereas the second solution is an innovative model of cable-driven micro-macro robot. In the first part of the thesis, the kinematic and dynamic models of these innovative systems are presented and analyzed in order to characterize their capability. Trajectory planning and optimal design are addressed with the purpose of maximizing the performance of the systems. The last part of the thesis deals with the design of a novel family of Intelligent CAble-driven parallel roBOTs whose architecture and control are conceived to maximize the robot versatility to the task to be performed and the environment in which the robot is intended to operate.La crescente necessitá di far fronte a produzioni industriali caratterizzate da elevata personalizzazione richiede elevata flessibilitá dei sistemi di produzione e assemblaggio. Una delle soluzioni piú interessanti consiste nell’idea di combinare le capacitá manuali di un operatore con le potenzialitá tipiche di sistemi robotici per consentire una collaborazione efficace. Al giorno d’oggi, in ambiente industriale, lo spazio operativo in cui operano sistemi ad elevata automazione é marcatamente separato dallo spazio operativo in cui puó muoversi un operatore umano, tuttavia le recenti normative prevedono la possibilitá che questi due soggetti collaborino all’interno di uno spazio condiviso. Sulla base di un’approfondita ricerca bibliografica, in cui é emerso l’elevato interesse da parte della comunitá scientifica e industriale nelle applicazioni di cooperazione uomo-robot, abbiamo deciso di analizzare il problema della movimentazione di carichi in ampi spazi di lavoro per l’asservimento agli operatori. I robot collaborativi presenti sul mercato sono tipicamente caratterizzati da carichi trasportabili e spazi di lavoro ridotti che ne riducono il potenziale impiego. Tali aspetti possono superare i pregi dovuti alla collaborazione e renderla inefficace. L’obiettivo del progetto é, quindi, lo studio ed il progetto funzionale di sistemi meccatronici innovativi capaci di incrementare lo spazio operativo e la versatilitá del sistema con lo scopo finale di creare una collaborazione uomo-robot efficace. Considerando le grandi aree di lavoro, la possibilitá di operare in ambienti industriali in cui possono essere presenti ostacoli e l’elevato carico utile che potrebbe essere necessario, i robot cavi rappresentano una valida soluzione. Inoltre, la possibilitá di riconfigurare rapidamente il sistema (online oppure offline) e la loro semplicitá costruttiva li rende attraenti anche dal punto di vista economico. Il lavoro svolto durante il percorso di dottorato ha permesso di individuare due soluzioni innovative di robot a cavi capaci di ingrandire lo spazio di lavoro, aumentare la versatilitá le sistema e ridurre i rischi di collisione. La prima soluzione consiste in un robot a cavi sospeso con end-effector riconfigurabile mentre la seconda soluzione é un innovativo modello di Micro-Macro Robot attuato a cavi. Sono stati sviluppati ed analizzati i modelli cinematici e dinamici di questi sistemi con l’obiettivo di caratterizzarne le proprietá. Inoltre, sono stati affrontati i problemi di pianificazione della traiettoria e di ottimizzazione del sistema. Per dimostrare le enormi possibilitá caratterizzanti i robot a cavi, é stato sviluppato un software di progettazione. Tale software é caratterizzato da un simulatore con il quale é possibile configurare rapidamente il layout di un robot a cavi e valutarne le prestazioni in termini di prestazioni cinematiche e dinamiche. Inoltre é possibile simulare movimenti e valutare eventuali collisioni con gli ostacoli presenti nell’ambiente operativo. Il simulatore é stato realizzato con lo scopo di sviluppare una nuova famiglia di robot a cavi intelligenti (ICABOT, Intelligent CAble RoBOT) la cui architettura é concepita per massimizzare la versatilitá del sistema rispetto al compito da esguire e all’ambiente in cui deve operare. Un prototipo in ICABOT é stato sviluppato presso il laboratorio di Robotica dell’Universitá di Padova. Tale prototipo é costituito da componenti meccanici modulari e da un’architettura di controllo EtherCAT basata sulle piattaforme Matlab e Twincat 3

Trajectory planning of a suspended cable driven parallel robot with reconfigurable end effector

In this paper, a new suspended cable driven parallel robot (CDPR) with reconfigurable end effector is presented. This robot has been conceived for pick and place operations in industrial environments. For such applications, the possibility to change the configuration of the cables at the end-effector level is a promising way to avoid collisions with obstacles in the approaching phases, while reducing at the same time the duration of motion in the remaining part of the trajectory. An optimized trajectory planning algorithm is proposed, which implements a pick and place operation in the operational space with dynamic on-line reconfiguration of the end effector. The results on a simplified scenario demonstrate the ability of the system to obtain reduced movement times together with obstacle avoidance

Throughput maximization and buffer design of robotized flexible production systems with feeder renewals and priority rules

Automation is a powerful way to reduce production costs. The growing market demand for a wide set of models and small batch production make flexible automated production systems an emerging need in several industries. The aim of this paper is to analyze and to maximize the performance of robotized flexible production systems consisting of a robot, feeder, working station, and unloading station, where the operations of the working cycle are scheduled using a sequencing algorithm based on priority rules. Since the working cycle is not predefined, the cycle time is strongly influenced by the parameters characterizing the workcell such as the workcell layout, the robot transfer movements, the feeder, the working operations, and the presence of a buffer between stations. In this work, we modeled the working cycle of a simple but representative layout of an industrial robotized flexible production system with and without buffer, and we implemented a recursive algorithm to estimate the cycle time. The analytical model derived was compared to the experimental results, obtained by using a prototype of the flexible production workcell. The results show that the analytical model is a powerful tool to estimate the performance of the workcell and to identify the design variables or their combinations that maximize the throughput

Optimal design of compact organic Rankine cycle units for domestic solar applications

Organic Rankine cycle turbogenerators are a promising technology to transform the solar radiation harvested by solar collectors into electric power. The present work aims at sizing a small-scale organic Rankine cycle unit by tailoring its design for domestic solar applications. Stringent design criteria, i. e., compactness, high performance and safe operation, are targeted by adopting a multi-objective optimization approach modeled with the genetic algorithm. Design-point thermodynamic variables, e. g., evaporating pressure, the working fluid, minimum allowable temperature differences, and the equipment geometry, are the decision variables. Flat plate heat exchangers with herringbone corrugations are selected as heat transfer equipment for the preheater, the evaporator and the condenser. The results unveil the hyperbolic trend binding the net power output to the heat exchanger compactness. Findings also suggest that the evaporator and condenser minimum allowable temperature differences have the largest impact on the system volume and on the cycle performances. Among the fluids considered, the results indicate that R1234yf and R1234ze are the best working fluid candidates. Using flat plate solar collectors (hot water temperature equal to 75 °C), R1234yf is the optimal solution. The heat exchanger volume ranges between 6.0 and 23.0 dm3, whereas the thermal efficiency is around 4.5%. R1234ze is the best working fluid employing parabolic solar collectors (hot water temperature equal to 120 °C). In such case the thermal efficiency is around 6.9%, and the heat exchanger volume varies from 6.0 to 18.0 dm3